Refill fuse plug



June 24, 1941.

J. CREE ET AL.

REFILL FUSE PLUG Filed Sept. 22, 1938 GOGGOOG- InUEnt. Errr E J. CREE EDRL-ETT Patented June 24, 1941 REFILL FUSE PLUG John Cree, Hamilton,Ontario, and Frank Corlett,

Crowland, Ontario, Canada, assignors of onethird to Earle T. Bradlield,Hamilton, Ontario,

Canada Application September 22, 1938, Serial No. 231,240

6 Claims.

A still further object is to provide a lock for n the metallic screwshell of the plug so that the latter will not become disengaged from thescrew of the insulating body of the plug during the unscrewing of theplug from the metallic screw shell .I

of the fuse block or holder.

With the above and other objects in view which will hereinafter appearas the specification proceeds, our invention consists in its preferredembodiment, of the construction and arrangement all a-s hereinafter moreparticularly described and illustrated in the accompanying drawing inwhich- Fig. 1 represents a vertical section through a fuse holder of thescrew shell type showing our refill fuse plug screwed thereinto.

Fig. 2 is a side view of our plug taken at right angles to Fig. 1.

Fig. 3 is a vertical section of our plug taken on the line 3-3 (Fig. l),the plug being removed from the fuse holder.

Fig. 4 is a vertical section taken on the line 4 4 (Fig. 2).

Fig. 5 is an inverted plan view of our plug.

Figs. 6 and 7 are respectively side and inverted plan views of theinsulating body of the plug.

Figs. 8, 9, and 10 are respectively side, plan and inverted plan viewsof the capsule inserted into the body of the plug and supporting thefuse element, and

Fig. 11 is a plan View of the fuse element.

Like characters of reference indicate corresponding parts in thedifferent views of the drawing.

Our refill fuse plug comprises an exterorly screw threaded cylindricalbody I preferably composed of heat resisting glass with a peripheralflange 2 (by means of which the plug is screwed into and unscrewed fromthe fuse holder) at its closed end which is of reduced thickness toconstitute a window 3 for the inspection of the fuse element. 'Ihe otherend of the cylindrical body is open and its lip is provided with a notch4.

The capsule 5 of insulating material such as porcelain is generallycylindrical in shape and has a circumferential flange 6 therearoundintermediately of its length with a lug I formed on the upper face ofsuch flange and adapted to be received into the notch 4 when the capsuleis inserted into the interior of the body I with the iiange 6 resting onthe lip thereof. The upper part 8 of the capsule wall has a flatexternal groove 9 at one side registering at its lower end with a slotI0 extending through the flange 6, and at the other side a vertical slotII extending down from the upper end of the upper part of the capsule tothe vicinity of the ange.

The lower part I2 of the capsule has a flat face I3 at one side bevelledoff at its free end and a central electrical contact I4 extends axiallythrough the lower end of the lower part of the capsule and is riveted tothe offset lower end I5 of a conducting post I6 which extends up intothe slot I I and supports one end of the fuse element I 'l which isforked and straddles a set screw I3 in the upper extremity of the postI6. The fuse element II extends from the post I6 diarnetrically acrossthe upper end of the capsule, through a notch I9 and down in the groove9, through the slot It in the flange 6, its other end 20 being turnedover outwardly to abut the lower face of the flange 6.

The metallic screw shell 2l having an inturned flange 22 at its outerend dening a central circular opening to receive the lower part of thecapsule is threaded onto the body I until its flange 22 abuts the flangeof the capsule and makes electrical contact with the end 20 of the fuseelement I'I, a slight protuberance 23 being formed on the upper face ofthe flange 22 to make better contact between flange 22 and fuse elementend 20.

In order to prevent the metallic screw shell 2l from unscrewing itselffrom the body I when the plug is unsorew`ed from the metallic screwshell 24 of the fuse block or holder 25, a lock plate 26 adapted to lieon the flange 22 of the screw shell 2I and pivoted at one end theretohas its inner edge straight abutting the flat face I3 of the lower partof the capsule and its outer edge arcuate `so as to register with theperipheral edge of the screw shell 2|. So long as the screw shell 2I isdisposed in the screw shell 24 of the fuse block or holder 25, thelatter shell will retain the lock plate 26 in engagement with the flatface I3 on the lower part of the capsule and consequently the screwshell 2| will be prevented from turning relatively to the body I.However, upon the plug being removed from the fuse block or holder, thelock plate will be ineffective to hold the screw shell 2 I in positionand it may be unscrewed from the body I, the capsule 5 then beingremoved and the blown fuse replaced by a new one.

In replacing the fuse element it is only necessary to attach the forkedend of the new fuse element to the post by the set screw I8, then bendthe fuse element diametrically across the top of the capsule into thenotch I9 and down into the groove 9 pushing the free end 20 through theagainst the lower face of the capsule flange 6 wherein it contacts theflange 22 of the screw shell 2| when the capsule has been inserted intothe body I and the screw shell 2| has been threaded thereover. The lockplate 26 is then swung inwardly until its straight inner edge abuts theflat face I3 on the lower part of the capsule when the plug is ready forinsertion into the fuse block or holder.

The bevel on the flat face I3 on the lower part I2 of the capsule 5facilitates the bending over of the end 20 of the fuse element II bypermitting the insertion of a finger nail or thin instrument betweensuch flat surface I3 and the inner face ofthe Yend 20 of the'fuseelement.

What I claim as my invention is:

1. A refill fuse plug comprising an externally threaded hollow body ofinsulating material open at one end, a hollow fuse element carryingcapsule of insulating material open at one end and having a peripheralflange extending therearound intermediatelyV of its length with a `fuseelement receiving slot therethrough in proximity to the outer wall ofthe capsule, the open ended portion ofthe capsule being inserted intothe body with the flange abutting the open end thereof, a contact postextending longitudinally in the interior of the capsule, a centralcontact extending through the outer end of the capsule and secured toone end of the contact post, a continuous integral fuse elementdetachably secured at oneend to the other end of the contact post andextending diametrically across the open end of the capsule anddownwardly along its outer wall with the other end of such continuousintegral fuse element protruding through the'slot in 'the flange andbent outwardly against the lower surface of such flange, a screwthreaded shell of conducting material with an inwardly turned flangedening a central opening receiving the outer portion of the capsule,said shell being screwed `onto the -screw threaded body with its flangein abutment with'the flange on the capsule and such screw threaded shellflange making electrical contact with but mechanically unsecured to theoutwardly bent end of the fuse element lying against the flange of thecapsule, and means for locking the screw threaded shell against rotationrelatively to the body only when the plug is being unscrewed 'from `thescrew threaded shell of a fuse block or holder.

2. A refill fuse plug `corruslrising an externally threaded vhollow bodyof insulating material open at-'one end, a hollow fuse element carryingcapsule vof insulating material open at one end and having aperipheralilange extending therearound intermediately of its Alength with a 'fuseelement receiving slot therethrough ,in proximity to the outer wall ofthe capsule, the open ended pontion of the capsule being inserted intothe body with the flange abutting the open end thereof, a contact'postextending longitudinally inthe interior of the capsule, a centralcontact extending through the outer end of Ythe capsule and secured toone end of the contact post, a continuous integral fuse elementdetachably secured at one-end to the other end of the contact post andext-ending diametrcally across the open lend of Y the capsule anddownwardly along its outer wall with the other end of such continuousintegral 'fuse element protruding through the :slot inthe flange andbent outwardly against the lower surslot I0 in the flange and bending itoutwardly face of such flange, a Screw threaded shell of conductingmalterial with an inwardly turned flange defining a central openingreceiving the outer portion of the capsule, said shell being screwedonto the screw threaded body with its llange in abutment with ftheflange on the capsule and such screw threaded shell flan-ge makingelectrical contact with but mechanically une secured to the outwardlybent end of the fuse elementlying against the ilange of the capsule, aflat side on the outer portion of the capsule, and a, swingable lockingplalte mounted on the flange of the screw threaded shell and engageablewith said at side of the outer portion of the capsule for locking thescrew threaded shell against rotation relatively to the body whentheplug is being unscrewed Vfrom the screw threaded shell of a fuse blockor holder.

3. In a refill fuse plug, in combination, anexternally threaded hollowbody of insulating material open at one end, a fuse element carryingcapsule of insulating material inserted into such body with one endprotruding therefrom, a screw threaded shell screwed onto the body forholding the capsule therein, and lmeans for locking 'the screw threadedshell against rotation relatively to the body-only when the plug isbeing unscrewed from the screw'threaded shell of a, fuse block orholder.

4. In a refill fuse plug, in combination, an externally threaded hollowbody of insulating material open `at one end, a fuse element carryingcapsule of insulating material inserted into such body with one endprotruding therefrom, a screw threaded-shell screwed onto the body'forholding the capsule therein, a flat side on the protruding end of thecapsule, and aswingable locking plate on the screw threaded shellengageable with lthe flat side of-the protruding end of the capsule forlockingthe screw threaded shell against rotation relatively to the-bodywhen the plugis being unscrewed from the screw threaded shell of a fuseblock or holder.

5. rThe invention claimed in claim 4 wherein the'screwthreaded shell hasan inwardly turned flange defining a central opening through which theprotruding end of the capsule extends, and such swingable locking plateis mounted on such flange.

`6. The combination with the screw threaded shell fof a fuse block orholder, of a refill fuse comprising an externally threaded body ofinsulating-material open `at one end, a fuse element `carrying capsuleof insulating material inserted into such body with one end protrudingtherefrom, a -screw threaded lshell screwed onto the 'body for holding`the'capsule therein, said screw threaded shell having an inturnedflange defining a central opening receiving the protruding end of thecapsule, a flat side on the protruding end of the capsule, a swingablelocking plate on the flange of the `screw threaded shell having astraight inner edge engageable `with the flat side on the protrudingVend of the capsule, and a curved `outer edge conforming with theperipheral curvature of the shell whereby the locking plate is-heldinengagement lwith the flat side of the protruding end of the capsulelwhen the plug is located in the screw threaded shell of the fuse block`or holder.

JOHN CREE. FRANK' CORLE'IT.

